1. Field of the Invention
This invention relates to data content identification. Examples of such content include one or more of video content, audio content, metadata content, text content, image content and so on, such as audio visual content.
2. Description of the Prior Art
The growth of new digital infrastructures, including digital devices and high-speed networks, combined with increasing processor power, is making content creation, manipulation and distribution both simpler and faster. While this greatly aids legitimate usage of the content, a disadvantage is that unauthorised abuse or “piracy” of such content (particularly copyright content), such as unauthorised reproduction or distribution, is also becoming easier and more damaging to the content owner.
The situation is made more complicated in that commercial considerations may require the content owner to allow a potential customer to see or use the content in a trial situation—perhaps as part of a professional review of the content or before committing to purchase rights to use the content from the owner. In the case of, for example, a movie film, very many copies of the content may be distributed in this way.
It has been proposed that a so-called “fingerprinting” technique is used to apply identification data to the content. While this does not prevent unauthorised copying, it can allow the source of the unauthorised copies to be detected. Examples of a fingerprinting technique applicable to video signals are described in GB-A-2383221 and U.S. Pat. No. 5,664,018.
However, this technique can take a long time to carry out. Using current technology at the priority date of this application, it can take up to, say, ten hours to apply the fingerprint processing to a full length movie film.